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Subject: Re: [boost] [asio] Randomly having problems reading from the socket
From: FlorianGeorge (fgeorge_at_[hidden])
Date: 2012-04-02 17:11:04

I am also having the problem that in my application, sending/receiving at
20Hz over a localhost/loopback connection, sometimes stalls for exactly
5000ms. This happens mostly on slower (e.g. Athlon X2 4400+) than on faster
(e.g. i7-930) machines.

Torben Wiggerich wrote
>> Have you put an analyzer (e.g. WireShark) on it and watched the TCP
>> packets from right before and when the pause occurs? This might help
>> isolate the problem.
> Ok I will try this...
Did this help finding the source of the problem?

As explained here (,
Wireshark/WinPcap will not be able to capture traffic over the loopback
device. As suggested, I used RawCap (

I filter the data using "tcp.port == 1234" to not get sidetracked by other

I uploaded a screenshot here:
I uploaded the whole dumpfile here:

The interesting part is probably this:

> 85030 16.690429 TCP 1500 [TCP segment of a reassembled
> PDU]
> 85041 21.689453 TCP 808 [TCP Previous segment lost]
> [TCP segment of a reassembled PDU]

You can clearly see the ~5000ms pause between those two events.

Does anyone have further insight in the reason why it is exactly 5000ms, and
how to maybe fix or work around it?

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